Method for the production of a semi -finished product for a wing-shaped element

ABSTRACT

Method for producing a semi-finished product for a wing-shaped element having, a front and rear edge, an arched bottom and a top wall that extends some distance apart between the front edge and the rear edge, includes: 
         bending the sheet by forming two panels ( 3, 4 ) and a curved region which the panels adjoin, placing a former in the bent sheet with the front edge of the former positioned in the curved region, forcing a pressure member towards a rubber cushion with the bent sheet enclosed therebetween and deforming the sheet, placing the shaped sheet in a rubber press including a bottom block having a cavity with a shape approximately corresponding to the of one of the walls of the shaped sheet, pressing the shaped sheet with former between the bottom block and a rubber mat, removing the semi-finished product from the rubber press.

The invention relates to a method for the production of a semi-finishedproduct for a wing-shaped element and of the wing-shaped element itself.Such wing-shaped elements are found in many different embodiments. Aso-called vane, which is fixed to a flap of an aircraft wing, ismentioned as an example.

Various production methods for such wing-shaped elements are known.Extrusion of the element is mentioned first. In such a case the elementdoes not have to be made up of separate components, which is quick andrelatively inexpensive. The disadvantage, however, is that thedimensional tolerance is poor. This arises, in particular, in the caseof relatively small thicknesses. According to a further known method theelement is produced from sheet material. After pre-forming the sheetmaterial, this is stretched on a stretcher leveller for making sectionsthat has a bottom block and top block. A mandrel is incorporated in thepre-formed sheet material. The whole is clamped at the longitudinal endsand then stretched. The disadvantage of this known method is that thesurface obtained has irregularities.

The aim of the invention is to provide a method for the production of asemi-finished product for a wing-shaped element that does not have thesedisadvantages. Said aim is achieved by means of a method for theproduction of a semi-finished product for a wing-shaped element having,in cross-section, a front edge, a rear edge and an arched bottom walland an arched top wall that extend some distance apart between the frontedge and the rear edge, comprising the following steps:

providing a metal sheet,

bending the sheet with the formation of two panels as well as a curvedregion which the panels adjoin,

providing a former, the exterior of which has the shape of the internalsurface of the finished section,

placing the former in the bent sheet with the front edge of the formerpositioned in the curved region,

providing an edge press provided with a pressure member and a rubbercushion located opposite,

fixing the former to the pressure member,

forcing the pressure member towards the rubber cushion with the bentsheet enclosed between them and deforming said sheet between the formerand the rubber cushion,

removing the former with shaped sheet from the edge press,

placing these in a rubber press provided with a bottom block having acavity which has a shape that at least approximately corresponds to theexternal shape of one of the walls of the shaped sheet,

pressing the shaped sheet with former between the bottom block and arubber mat,

removing the semi-finished product from the rubber press.

With the method according to the invention the semi-finished product isshaped by exerting pressing forces thereon via rubber elements. Incombination with the former acting as a mandrel that has the correctcontour, an extremely accurate shape is obtained by this means which hasa surface that has the smoothness desired for aircraft for aerodynamicreasons.

The two panels are preferably arched after, or before, or at the sametime as bending the sheet. The arching can be oriented in the samedirection in order to obtain a relatively strong curved element.However, the archings can also be oriented away from one another.

Bending and optionally arching the panels can be effected by means ofroller forming or by means of rolling. The rear edge of the element canbe made as a section that is fixed to the top wall and the bottom wall.Furthermore, the wing-shaped element can be subjected to a heattreatment, for example stress-free annealing or solution annealing.

The invention also relates to a wing-shaped element produced inaccordance with the method according to the method described above,which element, for example, can be made as a vane.

Reference is made to the wing-shaped element that is disclosed in U.S.Pat. No. 4,531,270. This element is produced from a relatively flatsection that comprises two panels that form a whole and in which thearching of the ultimate walls has been pre-produced by a locally greatermaterial thickness. The element is obtained from this by simply foldingthe panels onto one another, after which the element is ready. Theelement concerned here is in the form of a blade for turbines.

The invention will be explained in more detail below with reference toan illustrative embodiment shown in the figures.

FIG. 1 shows a curved and arched sheet that serves as starting materialfor the method according to the invention.

FIG. 2 shows the element in an edge press.

FIG. 3 shows the result after performing a treatment in the edge press.

FIG. 4 shows a perspective view of the rubber press block of a rubberpress, with the mandrel.

FIG. 5 shows the product obtained after rubber pressing.

FIG. 6 shows the finished wing-shaped element.

When carrying out the method according to the invention the startingmaterial used is the bent sheet 1 shown in FIG. 1, which has been bentwith the formation of a bent front edge 2, a concave arched panel 3 anda convex arched panel 4. This bent sheet 1 is placed in the edge press 5shown in FIG. 2, which has a base 6 with rubber cushion 7 as well as apressing member 8 that can be moved up and down and to which the former10 is fixed by means of the supports 9. This former 10 or mandrel 10 isalso shown in a perspective view in FIG. 4. It has the shape of theinternal surface of the finished wing-shaped element, that is to saywith a front edge, rear edge and arched top surface and bottom surface.The former can have a prismatic shape but also a twisted shape.

When pressing the bent sheet 1 in the edge press, the front edge of theformer 10 is pushed into the curved region 2 of the sheet 1. By thismeans this curved region is curved more severely around the front edgeof the former 10, under the influence of the even inward pressure by therubber cushion 7. As a consequence of this, the arched panels 3 and 4come closer together, as shown in FIG. 3.

The sheet 1 further shaped in this way is then placed in a rubber press,the rubber press block 11 of which can be seen in FIG. 4, the interiorshape of which corresponds to the front edge and an arched surface ofthe wing-shaped element. Together with mandrel 10, the sheet 1, whichnow has the shape as shown in FIG. 3, is placed in this rubber pressblock 11. The rubber mat 12 is then placed on top of the whole of this,after which the sheet 1 with the mandrel 10 therein is compressedbetween the rubber press block 11 and the rubber mat 12 by a press (notshown).

After rubber pressing, the semi-finished product 13 shown in FIG. 5 isobtained, which has a curved front edge 2, a convex arched top surface 2and a concave arched bottom surface 3. Finally, the section indicated inits entirety by 14 is fixed to the rear, free ends of the walls 2, 3.For this purpose the section has a body 15 with sides 16, 17 taperingdown with respect to one another that are oriented in accordance withthe run of the top wall 2 and the bottom wall 3. The section 14 is fixedto the semi-finished product 13 by means of rivets 18 driven through thetop wall 2, the body 15 and the bottom wall 3, after which thewing-shaped element 15 is ready. As an alternative, the walls 2, 3 canalso be fixed directly to one another, such as by bonding, riveting andthe like.

1-15. (canceled)
 16. Method for the production of a semi-finishedproduct (13) for a wing-shaped element (15) having, in cross-section, afront edge (2), a rear edge (14) and an arched bottom wall (3) and anarched top wall (4) that extend some distance apart between the frontedge (2) and the rear edge (14), comprising the following steps:providing a metal sheet (1), bending the sheet (1) with the formation oftwo panels (3, 4) as well as a curved region (2) which the panels (3, 4)adjoin, providing a former (10), the exterior of which has the shape ofthe internal surface of the finished element (15), placing the former(10) in the bent sheet (1) with the front edge of the former (9)positioned in the curved region (2), providing an edge press (5)provided with a pressure member (8) and a rubber cushion (7) locatedopposite, fixing the former (10) to the pressure member (8), forcing thepressure member (8) towards the rubber cushion (7) with the bent sheet(1) enclosed between them and deforming said sheet between the former(10) and the rubber cushion (7), removing the former (10) with shapedsheet (1′) from the edge press (5), placing the shaped sheet (1′) in arubber press provided with a bottom block having a cavity (16) which hasa shape that at least approximately corresponds to the external shape ofone of the walls (3, 4) of the shaped sheet (1′), pressing the shapedsheet (1′) with former (10) between the bottom block (11) and a rubbermat (12), removing the semi-finished product (13) from the rubber press.17. Method according to claim 16, wherein the two panels (3, 4) arearched after, or before, or at the same time as bending the sheet (1).18. Method according to claim 16, comprising bending the curved region(2) and optionally arching the panels (3, 4) by means of roller forming.19. Method according to claim 16, comprising bending the curved region(2) and optionally arching the panels (3, 4) by means of rolling. 20.Method according to claim 16, comprising constructing the rear edgeusing a section (14) that is fixed to the top wall (3) and the bottomwall (4) with the formation of a wing-shaped element (15).
 21. Methodaccording to claim 16, including a heat treatment step, such asstress-free annealing or solution annealing of the semi-finished product(13).
 22. Wing-shaped element (15) produced in accordance with themethod according to claim 16 made as a vane.
 23. Element (15) accordingto claim 22 as produced by means of the method according to claim 5,wherein the section (14) has a body (19) that extends between the panels(3, 4).
 24. Element (15) according to claim 23, wherein the panels (3,4) and the body (19) are fixed to one another by rivets (18), bondingand the like.
 25. Element (15) according to claim 23, wherein thesurfaces (16, 17) of the body (19) facing away from one another runobliquely with respect to one another in accordance with the run of thepanels (3, 4).
 26. Element (15) according to claim 22, wherein thepanels (3, 4) are fixed directly to one another.
 27. Element (15)according to claim 22, comprising a sheet (1) with a thickness in therange of 0.8-2.0 mm.
 28. Element (15) according to claim 27, comprisinga sheet (1) with a thickness in the range of 1.4-1.6 mm.
 29. Element(15) according to claim 27, comprising a sheet (1) with a thickness inthe region of 1.6 mm.
 30. Element (15) according to claim 22, comprisinga sheet material consisting of Al, Ti, Sc, Cu, Mg, Li and/or alloysthereof and/or steel and/or stainless steel.